CNS Cell Fibers, Types, & Spinal Cord

What cells make up a majority of the nervous system?

neuroglia

Which type of neurons have unipolar morphology?

sensory neurons

Where is the soma of sensory neurons found?

outside the CNS

some cell bodies of CN V

Where are bipolar cells found in the body?

found in the retina

What morphology do motor neurons have?

multipolar neurons

Where are the multipolar neuron cell bodies found?

in ventral root of the spinal cord (CNS)

or motor nuclei of cranial nerves

Where does a central process of a unipolar neuron travel?

from ganglion to brain/spinal cord

Where does the peripheral process of a unipolar neuron travel?

from ganglion to periphery

nuclei

collection of cell bodies in the CNS

centers

collections of neuron cell bodies in the CNS; each center has specific processing functions

ganglia

Collections of cell bodies in PNS

capsules

layer of white matter than surrounds gray matter

tracts

bundles of axons in the CNS

lemnisci

tracts in CNS that are flattened, ribbon like

columns

round collection of white matter

What are the processes of the PNS called?

nerves

What are the support cells of the CNS?

astroglia microglia

oligodendrocytes

What are the support cells of the PNS?

Schwann cells

ependymal cells

line cavities of the brain and spinal cord, circulate cerebrospinal fluid

What is the embryological derivation of the support cells of the CNS?

neural tube

What is the embryological derivation of the support cells of the PNS?

neural crest cells

What is the embryological derivation of ependymal cells?

neural tube

What are the functions of astrocytes?

maintains shape of CNS

maintains ionic homeostasis of interstitial space

glutamate removal

blood brain barrier

gliosis

What type of junctions help form the blood brain barrier?

tight junctions

gliosis

proliferation of astrocytes in an area of neuron degeneration leading to a glial scar

glial scar

astrocytes mites and fill in area of necrosis

glial cyst

astrocytes surrounds fluid an form a cyst

What is the number one primary brain tumor?

astroglioma

Astrocytes

benign bc not metastatic but can still be fatal if compresses vital centers

Which cell controls the immune response of the CNS?

microglia

What cells are microglia derived from?

derived from mononuclear phagocytic system

What is the function of oligodendrocytes?

produce myelin in CNS

one cell can put out multiple processes to myelinate many axons

Which cell makes myelin for cranial nerve I & II?

oligodendrocytes

Which cell makes myelin for cranial nerve V?

Schwaan cells

Which cells do multiple sclerosis target?

oligodendrocytes

What are the two types of multiple sclerosis?

Remitting-relapsing MS

Progressive MS

Where are plaques caused by multiple sclerosis most likely found?

paraventricular

juxtacortical

infratentorial

spinal cord

medial longitudinal fasiculus

interconnects occulomotor, trochlear, abducens, and vestibular nerve

What would MS damage to the medial longitudinal fasiculus cause?

transiet diplopia upon eye movement

Macdonald criteria

used to diagnose relapsing and remitting MS

two lesions disseminated in time and space

*can be diagnosed using MRI with and without contrast

What are the characteristics of primary progressive multiple sclerosis?

characterized by a fairly steady, gradual change in functional ability over time, most often related to walking

What is the criterion for diagnosis of primary progressive multiple sclerosis?

one year of disease progression without remission

and two of the following:

a type of lesion in the brain that is recognized by experts as being MS

two or more lesions of a similar type in the spinal cord

evidence in the spinal fluid of oligoclonal band or elevated IgG index, both of which are indicative of immune system activity in the central nervous system

optic neuritis

presents as acute onset vision loss, usually unilaterally

if occurs could be at increased risk of developing multiple sclerosis

Internuclear ophthalmoplegia

a lesion of the medial longitudinal fasciculus (MLF); most commonly due to MS plaques when presenting in a young person

What is the risk for patients with optic neuritis for developing MS over 10 years after a single case of optic neuritis?

38%

What is the risk for patients with optic neuritis for developing MS over 10 years after a single case of optic neuritis and if they have a brain lesion?

56%

What is the risk for patients with optic neuritis for developing MS over 10 years after a single case of optic neuritis and no brain lesion?

22%

How many Schwaan cells wrap one axon?

one Schwaan cell myelinates one axon

choroid plexus

double fold of ependymal cells that become choroid epithelial cells with pia mater blood vessels in the middle of the

makes all CSF

Where is CSF made in the lateral ventricle?

body and inferior horn

Where is CSF made in the third ventricle?

roof

Where is CSF made in the fourth ventricle?

roof

Guillain-Barre syndrome

autoimmune condition that causes acute inflammation of the peripheral nerves in which myelin sheaths on the axons are destroyed, resulting in decreased nerve impulses, loss of reflex response, and sudden muscle weakness

can occur after viral infections or immunization

neurolemma

the outermost nucleated cytoplasmic layer of Schwann cells that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system

endoneurium

delicate connective tissue around individual nerve fibers in nerve

perineurium

coarse connective tissue that bundles fibers into fascicles

forms blood nerve barrier which is not present at nerve endings

epineurium

DICT vascular sheath that wraps each nerve

vasa nevorum

small blood vessels that run inside epinerium of nerve

How is vasa nevorum affected in diabetes?

because vasa nevorum are small blood vessels they can become occluded and cause ischemia to a nerve

ex: 6th never palsy